Blindstitch sewing machine

ABSTRACT

In a blindstitch sewing machine adapted to selectively produce non-skip stitches or skip stitches whenever desired, adjustable means for determining the normal position of a rockable work support carrying a node former to enable the machine to properly provide either type of stitching in work of different thicknesses and foldability. Said adjustable means and members controlled thereby serve to readily and accurately determine the normal position of the work support and the extent of rocking movement imparted thereto in forming skip stitches. The adjustable means includes a rotatable knob, the turning of which to a given extent will always provide the same extent of adjustment of the work support about its supporting axis.

D United States Patent [151 3,677,208 Fletcher et al. [4 1 July 18, 1972 [54] BLINDSTITCH SEWING MACHINE [72] Inventors: Roy W. Fletcher, Riverdale; Anthony D. 522:? fg z zzgfi Hunter Fone, Chicago, both of 111. ey o [73] Assignee: Union Special Machine Company, ABSTRACT chlcago In a blindstitch sewing machine adapted to selectively produce 22 19, 19 non-skip stitches or skip stitches whenever desired, adjustable means for determining the normal position of a rockable work pp N05 753,357 support carrying a node former to enable the machine to properly provide either type of stitching in work of different 7 ddekdeeeee end feldebddw Sedd edjdedeele meede end 2 2 8 bers controlled thereby serve to readily and accurately deter- [58] Field 112/1 78 176 177 220 mine the normal position of the work support and the extent of rocking movement imparted thereto in forming skip [56] References Cited stitches. The adjustable means includes a rotatable knob, the

turning of which to a given extent will always provide the same extent of adjustment of the work support about its supporting axis.

Patgnted July 18, 1972 I 3,677,208

4 Sheets-Sheet l Patented July 18, 1972 4 Sheets-Sheet 2 Patented July is, 1972 3,677,208.

4 Sheets-Sheet 3 f Q Ll- Patented July 18, 1972 4 Sheets-Sheet 4 ill BLINDS'I'ITCH SEWING MACHINE This invention relates to a blindstitch sewing machine of the type adapted to produce various types of seams. It may be adjusted or controlled to produce a line of stitching, all of the stitches of which pass through several layers of fabric to be united. On the other hand, it may be adjusted to bring about skip stitches in a seam. Thus, when the control is shifted into a position to produce such a seam, alternate stitches may pass through the several layers to be united, and the other alternate stitches may simply penetrate the upper layer of the work pieces being fed through the machine. In the form of the invention to be disclosed, the arrangement is such that one skip stitch is provided after each regular or non-skip stitch when the control is shifted into the position to bring about skip stitches. However, the invention may be embodied in a machine adapted to produce two skip stitches after each nonskip stitch, if desired.

An important feature of the present invention is the provision of means for adjusting the depth to which the skip stitches and regular stitches penetrates one or more layers of fabric being dealt with. In constructions provided for this purpose heretofore, it has been found difficult to accurately adjust the means for controlling the depth of penetration of the thread into the one or more layers of work to conform with the requirements of fabrics of different thicknesses and foldability by the action of a node former.

The machine constructed in accordance with the present invention may be quite similar to that shown in the Roth et al. U.S. Pat. No. 3,288,094, granted Nov. 29, 1966. However, it incorporates an improvement upon the construction shown in that patent for bringing about the control over the depth of penetration of the various stitches into one or more layers of material that have been pushed upwardly by anode former.

More particularly, the invention is adapted to provide for accurate adjustment of the depth of penetration of the stitches into the one or more layers of material, by the rotation of a knob which has means connected therewith for varying the depth of penetration to substantially the same extent upon rotation of the knob through a particular arc. Thus, each 60 of rotation of the knob, for example, will bring about the same change in the depth of penetration of the regular stitches and the skip stitches into the layer or layers of material being dealt with. This enables the operator of the machine to quickly determine the setting of the control knob in dealing with work of different thicknesses and different foldability characteristics.

A special feature of the invention is the provision of a novel control over the means for rocking a conventional work supporting member of a blindstitch sewing machine, which member carries a node former. It will be understood that in the production of a skip stitch the work supporting member will be rocked downwardly to a sufficient extent to cause the stitch being formed to penetrate only the upper layer of the fabrics being stitched. On the other hand, when the work support is in its normal upward position, the node former will present the work being stitched into the path of the needle in such a way that the stitch will pass through the multiple layers of fabric being sewn. Here again, however, the control mechanism of the present invention makes it possible to accurately control proper passage of the thread through the multiple layers of material in accordance with their thickness.

With the foregoing purposes and features of the invention in mind, a preferred embodiment of the same will now be described in relation to the accompanying drawings in which:

FIG. 1 is a vertical sectional view through a portion of the frame of the machine embodying the invention, this view being taken along a plane parallel with the axis of the main drive shaft of the machine;

FIG. 2 is a vertical sectional view through a portion of the frame of the machine in a direction perpendicular to the axis of the main drive shaft of the machine, and shows in elevation a portion of the machine carrying the stitch forming and work feeding mechanisms;

FIG. 3 is a detail view, in vertical section, showing the means for imparting rocking movements to the work supporting member of the machine;

FIG. 4 is an elevational view of one of the elements through which rocking of the work support is brought about to produce skip stitches;

FIG. 5 is a side view of the member shown in FIG. 4, with a portion of the forward side of the same broken away to more clearly show the interior construction;

FIG. 6 is a view of the member shown in FIGS. 4 and 5 as seen from the right in FIG. 5;

FIG. 7 is a face view of an indicator plate and knob for determining whether skip stitches are to be formed;

FIG. 8 is a face view of a knob and related parts for adjusting the depth of penetration of the oscillating needle in relation to the noded work; and

FIG. 9 is a vertical sectional view through a portion of the work supporting member in the region of the node former.

As has been stated above, the machine embodying the invention that is illustrated in the drawings is of the general character of that disclosed in Roth et al. U.S. Pat. No. 3,288,094. As the description proceeds, it will be clear that various changes in certain portions of the machine disclosed in that patent have been made. The machine has a main frame provided with a base portion 10 adapted to rest upon a suitable table or the like. A vertical standard 11 rises upwardly from the base in a certain region thereof, and the upper end of this vertical standard has extending therefrom a horizontally disposed arm 12. Adjacent the free end of the arm 12, which is to the left of the portion shown in FIG. 1, there is a head 13 from which extends a forwardly and downwardly disposed arm 14, FIG. 2. The latter has its forward end disposed over the work supporting member of the machine, as will be more fully explained hereinafter. Within the horizontally extending arm 12 of the frame there is mounted a main drive shaft 15 which is suitably journaled in bearings provided in the frame of the machine. Shaft 15 extends outwardly from the frame at the right end, FIG. 1, and has secured thereto a combined hand wheel and pulley 16. As will be understood, this permits the drive shaft and the various operating parts within the machine to be operated manually for adjustment purposes and the like, and by a belt connection from a suitable power source such as an electric transmitter which drives the machine at a desired speed in the course of a stitch forming operation. At the forward end of the arm 14, which is the left end thereof as shown in FIG. 2, certain driving connections are provided for operating stitch forming devices including a needle 17 and a looper 17a. Also, suitable driving connections are provided for operating a feed dog 18 which serves to advance the work along the upper surface of the work supporting member. These elements of the machine may suitably be of the form disclosed in the Roth et al. patent mentioned above.

A toothed pulley 19 secured to the shafl 15 has a toothed belt 20 cooperating therewith. This belt also cooperates with a toothed pulley 21 mounted on a shaft 210 suitably disposed within the vertical standard 11. The shaft 21a is preferably held stationary, while the pulley 21 and connected parts are adapted to rotate freely about the shaft. Also mounted for rotation about the shaft 21a along with the pulley 21 are a concentric disc 21b and an eccentric element 210. The disc 21b may have integrally connected therewith, or otherwise connected into the assembly, a somewhat smaller diameter spacing member 21d. The various parts 21, 21b, 21c and 21d are secured together by screws 2le and this assembly is retained against any substantial axial movement along the shaft 21a by collars 21f secured to said shaft. In the particular machine illustrated in the drawings the toothed pulley 21 is of twice the diameter of pulley 19 so that the pulley 21 and connected parts will be given only one revolution for two revolutions of the main drive shaft 15.

A work supporting member 22 is rockably mounted on a shaft 23 fixedly secured to an extension 10a of the base of the frame of the machine. The work supporting member 22 has a shaft 24 which extends horizontally into a region adjacent the stitch forming zone of the machine. A member 25 is secured to the shaft 24 and is oscillated by a pitman 26, having a cylindrical bearing portion 26a at itsv right end (FIG. 2) which cooperates with an eccentric 26b. The latter is adapted to rotate about the axis of a shaft 28 which is fixedly mounted in the lower end of the vertical standard 11 of the frame. Also mounted for rotation about the shaft 28 is a toothed pulley 27 which is connected by a belt 29 with a toothed pulley 30 secured to the main drive shaft 15. The arrangement is such that for each revolution of the main drive shaft a revolution will be imparted to the pulley 27. The latter is connected with the eccentric 26b which in turn cooperates with the bearing portion 26a of the pitman 26 to impart rocking movement to the node former carrying shaft 24. As will be understood from the construction disclosed in the aforementioned Roth et al. patent, a node former is suitably connected with the shaft 24 for rocking movement by the. latter. The node former may be of a type having two active portions which may be selectively put into operative position in the manner explained in said Roth et al patent. One segment 25a of the node former is shown in FIG. 9. As the shaft 24 is rocked by the member 25 through a suitable arc, the node former 25a acts upon the work being advanced along the upper surface of the work supporting member 22 to present a node formed in the work in the path of the needle.

Means are provided in the machine for cooperation with either the eccentric portion 210 or the concentric portion 21b of the member connected with pulley 21 carried by the shaft 21a. Means for this purpose involves a fixed shaft 31 carried by the base of the frame of the machine and having collars 31a fixedly secured thereto at opposite sides of a bearing portion provided at the lower end of an upwardly extending arm 32. The latter has, at its upper end, a smooth flat hardened surface 32a (FIG. 2). Adjacent its lower end, but at a suitable distance above the shaft 31, the member 32 has a rounded surface 32b extending toward the left as shown in FIG. 3. The purpose of this will be explained hereinafter.

Cooperating with the upper end of the member 32 is a member 33 which is pivotally connected with a stud 33a carried by a member 33b which is retained in a fixed position, but may be adjusted manually in accordance with the thickness of the work being dealt with. Member 33b has a screw threaded extension adapted to cooperate with an internally screw threaded portion 34b of a manually adjustable means. The latter involves a knob 34 extending outwardly from the frame of the machine toward the operator. This knob is secured to a reduced portion 34a of the element having the internally threaded portion 34b. The arrangement is such that turning of the knob 34 in one direction or the other will serve to draw toward the left or push toward the right the element 33b that is pivotally connected with the stud 33a carried by the member 33. As shown in FIG. 8, the knob 34 is provided on its outer face with indicia adapted to cooperate with a fixed point on a plate carried by the frame to indicate the position to which the knob is turned. Also, as disclosed in the Roth et al. patent, a Geneva wheel arrangement is provided for turning an indicator which shows at 340 the number of revolutions of the knob from a starting position. In view of the accurate adjustment that is made in accordance with the present invention, upon the turning of the knob through a predetermined number of revolutions or a part of a revolution, it has been found that six revolutions of the knob are adequate to take care of the adjustment required in dealing with fabrics of maximum differences in thickness.

The member 33 is provided at its midpoint with a cylindrical pin 33c on which is rotatably mounted a roller or disc 33d, as best shown in FIG. 4. Roller or disc 33d is adapted for movement in an axial direction along the outer surface of the pin 330, in a manner to be explained, to bring it into cooperation with either the eccentric portion 210 or the cylindrical portion 21b of the member secured to the toothed pulley 21. Such shifting of the roller 33d is manually performed by a knob 38 connected with a stem 38a, which at its inner end has a U- shaped portion 38b adapted to straddle the roller 33d. Knob 38 is shifiable manually in the direction of the arrows indicated in FIG. 7.

As shown in FIG. 3, the member 32 has an arcuate surface 32b aligned with a slidable rod 35, and it is adapted to engage said rod to retain the latter in a desired position. The rod 35 has a collar 354 secured thereto and this is engaged by one end of a coiled spring 35b, the opposite end of said spring engaging a downward projection of the base 10 of the frame of the machine. As will be apparent the spring 35b serves to urge the rod 35 toward the right (FIG. 3) to cause the endof the rod to engage the surface 32b on member 32. The opposite end of the rod 35 is engaged by a screw element 36 having threaded engagement with a downwardly extending portion of the work supporting member 22. By turning the screw element 36 and then clamping it in a set position by a nut 36a the position of the work supporting member 22, angularly in relation to its pivotal axis 23, may be varied to present the top surface of the work supporting member and the node former carried thereby in a selected position in relation to the stitch forming devices. It will be appreciated, from the disclosure of the Roth et al patent, that a spring is provided to pull and rock the work supporting member in a counterclockwise direction (FIG. 2) to carry the inner'end of screw element 36 against the slidable rod 35. The spring for this purpose is indicated at 37 in FIG. I.

In the course of operation of the machine it may be adapted to produce alternate skip stitches and alternate non-skip stitches, or may be adapted to produce a continuous series of non-skip stitches. The latter result will be obtained if the knob 38 is shifted toward the right in FIG. 7. On the other hand, the alternate skip and non-skip stitches will be formed when the knob 38 is in the lefthand position. In connection with the foregoing, it should be understood that when the knob 38 is in the righthand position the disc 33d will cooperate with the concentric or cylindrical portion 21b of the element con nected with the toothed pulley 21'. Accordingly, no rocking of the elements 32 and 33 will take place on successive operations of the machine. 0n the other hand, when the knob 38 is shifted into the lefthand position shown in FIG. 7, the disc 33d will cooperate with the eccentric portion 21c. When this occurs, the members 33 and 32 will be rocked to a certain extent upon alternate revolutions of the main drive shaft 15. Thisis because during one revolution of said shaft, the disc 33d will cooperate with that portion of the circumference of part 210 which is concentric with the part 21b; however, during the next revolution of the drive shaft 15 the disc 33d will cooperate with that half of the part 21c which is slightly eccentric, so that this portion of the part 21c will rock the member 33 in a clockwise direction and in turn the latter will rock the member 32 in a counterclockwise direction about the axis of rod 31, to cause a slight shifting of the rod 35 toward the left (FIG. 3) and thus cause rocking of the work supporting member 22 through a slight angle in a clockwise direction (FIG. 2). Such rocking of the work supporting member 22 will bring about the production of the skip stitch during that revolution of the main drive shaft 15.

Returning now to the adjustability of the normal position of the members 32 and 33, by the turning of the knob 34, it will be noted from FIG. 2 that, if the knob 34 is turned into a position in which the pin 33a is shifted downwardly and toward the right, the member 33 will be rocked in a clockwise direction about the axis of the pin 33c which carries the disc 33d. The latter, of course, is held in a predetermined position by its engagement with the surface of either the concentric disc 21b or the eccentric disc 216. Accordingly, the lower portion of the member 33 will be swung toward the left from the position shown in FIG. 2, and in so doing the surface 33c (FIGS. 2 and 5) will cooperate with the flat surface 32a on member 32 and urge the latter toward the left. As a result of this, the surface 32b on themember 32 will urge the slidable rod 35 toward the left and cause a clockwise rocking of the work supporting member 22. In operation, the member 33 with its surface 33:

serves as a cam and member 32 with its surface 32a serves as a follower.

The surface 33e is provided on a hardened steel insert 33f secured to the lower portion of the member 33 by screw elements 33g. It has been found highly desirable to have the surface 33e in the form of an arc having about a 3-inch radius. This is substantially equal to the distance from the axis of the shaft 31 to the portion of the flat hardened surface 32a of the member 32 which cooperates with the arcuate surface 332. Moreover, the center of curvature of the surface 33e is disposed substantially along a line extending horizontally from the upper end of the arm 32, when the parts are in the position shown in FIG. 2. However, when the knob 34 is turned to place the axis of pin 33a downwardly and toward the right in FIG. 2, the center of curvature of the surfaces 33e will shift somewhat downwardly. In general, it may be said that this center of curvature of the surface 33e is along a line which extends from the point of contact of surfaces 32a and 33e in a direction perpendicular to a plane passing through the axis of shaft 31. and the axis of pin 33a.

In connection with the foregoing, it should be noted that the points on the flat smooth surface 320 at the upper end of member 32 and on the arcuate surface 33e which are in engagement with each other will be at a slightly lower point than that shown in FIG. 2 when the knob 34 is adjusted to shift the axis of pin 33a downwardly and toward the right.

It will be understood that, if desired, the machine may be so constructed that when the knob 38 is in the lefthand position (FIG. 7, two skip stitches will be produced after each non-skip stitch. For this purpose the toothed pulley 21 will need to be 3 times the diameter of the toothed pulley l9, and the part 21c will need to be so formed as to produce two skip stitches and one non-skip stitch upon each three revolutions of the main drive shaft.

While a preferred embodiment of the invention has been shown and described in some detail, it will be understood that various changes may be made in the construction of various parts of the machine within the scope of the invention, as defined by the appended claims.

What is claimed is:

1. In a blindstitch sewing machine having a main frame, a main drive shaft joumaled in the frame, a work support rockably mounted on the frame about a pivotal axis, a node former carried by the work support and a mechanism for rocking the support about its axis in response to operation of the main shaft including spring means for urging the support in one direction about its axis, the improvement wherein the mechanism also includes a pair of pivotally mounted levers other, the operative surface of one lever consisting of a circular arc and that of the other defining a straight line and means in the machine for uninterruptedly moving the point of contact between the levers smoothly along their operative surfaces to change the effective length of at least one of them, to thereby set the initial position of the work support and vary the amount of rocking movement imparted to the support when the machine is operated.

2. Apparatus according to claim 1 wherein the lever with the circular arc operative surface comprises the cam and the other lever comprises the follower.

3. Apparatus according to claim 1 wherein the circular are surface on the one lever has a radius of about three inches.

4. In a blindstitch sewing machine having a main frame, a main drive shaft joumaled in the frame, a work support rockably mounted on the frame about a pivotal axis, a node former carried by the work support and a mechanism for rocking the support about its axis in response to operation of the main shaft including spring means for urging the support in one direction about its axis, the improvement wherein the mechanism also includes a pair of pivotally mounted levers comprising an oscillatable cam having an operative surface consisting of a convex arc and a follower having a flat operatmg surface, the operative surfaces of both levers being in continuous single line contact with each other and means in the machine for uninterruptedly moving the point of contact between the cam and follower smoothly along their operative surfaces to change the effective length of at least one of them, to thereby set the initial position of the work support and vary the amount of rocking movement imparted to the support when the machine is operated.

5. Apparatus according to claim 4, wherein the pivotal mounting of the follower lever is below the point of contact with the cam lever and the work support rocking means includes a slidable member biased into engagement with the follower lever at a point between its pivotal mounting and its point contact with the cam.

6. Apparatus according to claim 5 wherein the follower lever has a predetermined length, the cam is pivotally mounted in a region above the follower and the operative surface of the cam has a circular arc curvature whose radius is about equal to the length of the follower.

7. Apparatus according to claim 15 wherein the circular arc surface on the cam has a radius of about three inches.

8. Apparatus according to claim 4 wherein the mechanism for rocking the work support about its axis includes an adjustable element to which the cam is pivotally connected, a rotatable knob mounted on the frame of the machine and connections from the knob to the adjustable element for shifting comprising cam and follower elements having operative Sun the latter to selectively position the pivot point of the cam.

faces which are in continuous single line contact with each 

1. In a blindstitch sewing machine having a main frame, a main drive shaft journaled in the frame, a work support rockably mounted on the frame about a pivotal axis, a node former carried by the work support and a mechanism for rocking the support about its axis in response to operation of the main shaft including spring means for urging the support in one direction about its axis, the improvement wherein the mechanism also includes a pair of pivotally mounted levers comprising cam and follower elements having operative surfaces which are in continuous single line contact with each other, the operative surface of one lever consisting of a circular arc and that of the other defining a straight line and means in the machine for uninterruptedly moving the point of contact between the levers smoothly along their operative surfaces to change the effective length of at least one of them, to thereby set the initial position of the work support and vary the amount of rocking movement imparted to the support when the machine is operated.
 2. Apparatus according to claim 1 wherein the lever with the circular arc operative surface comprises the cam and the other lever comprises the follower.
 3. Apparatus according to claim 1 wherein the circular arc surface on the one lever has a radius of about three inches.
 4. In a blindstitch sewing machine having a main frame, a main drive shaft journaled in the frame, a work support rockably mounted on the frame about a pivotal axis, a node former carried by the work support and a mechanism for rocking the support about its axis in response to operation of the main shaft including spring means for urging the support in one direction about its axis, the improvement wherein the mechanism also includes a pair of pivotally mounted levers comprising an oscillatable cam having an operative surface consisting of a convex arc and a follower having a flat operating surface, the operative surfaces of both levers being in continuous single line contact with each other and means in the machine for uninterruptedly moving the point of contact between the cam and follower smoothly along their operative surfaces to change the effective length of at least one of them, to thereby set the initial position of the work support and vary the amount of rocking movement imparted to the support when the machine is operated.
 5. Apparatus according to claim 4, wherein the pivotal mounting of the follower lever is below the point of contact with the cam lever and the work support rocking means includes a slidable member biased into engagement with the follower lever at a point between its pivotal mounting and its point contact with the cam.
 6. Apparatus according to claim 5 wherein the follower lever has a predetermined length, the cam is pivotally mounted in a region above the follower and the operative surface of the cam has a circular arc curvature whose radius is about equal to the length of the follower.
 7. Apparatus according to claim 15 wherein the circular arc surface on the cam has a radius of about three inches.
 8. Apparatus according to claim 4 wherein the mechanism for rocking the work support about its axis includes an adjustable element to which the cam is pivotally connected, a rotatable knob mounted on the frame of the machine and connections from the knob to the adjustable element for shifting the latter to selectively position the pivot point of the cam. 